I'm surprised no one has said this:
"Unless otherwise authorized by ATC, each person operating a large turbine engine powered airplane to or from a primary airport for which Class B airspace area is designed must operate at or above the designated floors of the class B airspace area while within the lateral limits of that area."
"Large turbine powered aircraft operating to and from a primary airport are prohibited from operating below the floor of any portion of class B airspace, unless specifically authorized by ATC. A visual approach does not consititue authorization to operate below the floor of class B airspace."
I've been flying out of Newark for over 10 years. I've never been near SBJ at 3000'- I'm always higher. I've never been "authorized by ATC to operate below the class B airspace." I've never seen glider NOTAMS. There are many glider airports and that means gliders- don't need a NOTAM for fly a glider. The Shaff arrival or V213 has many gliders. Just north of the Williamsport arrival and PENNS intersection has lots of gliders. And, of course, down by SBJ there are gliders. They have glider symbols on the sectional charts. Airline pilots don't have this info. See and avoid is the responsibilty of all pilots, but use common sense too. Don't fly on busy airline arrivals in or out of class B airspace. It's like a pedestrian crossing a busy intersection without the crosswalk green light.
There are also high power rocket launches on V213 near Shaff that fly on the first or second weekends of the month. They fly big rockets up to 12,000' and can reach speeds exceeding Mach 1-2. They are NOTAMed, but the airlines do not get these NOTAMS. Why? I don't know. Airliners pass this area at about 7,000' for Newark. Rocket flights over 5,000' are called into Boston Center for clearance. Plus, they look up before they launch the rocket. see
http://www.metrarocketclub.org/